Expansion chamber for pressure core barrels



`June 30, 1942. B. w. sEWLL EXPANSION CHAMBER' FOR PRESSURE coRE BARRELSFiledFeb. `1o, 1940 2 sheets-sheet 1 ATTORNEY.

June 30, 17942. B, SEWELL I 2,287,909

EXPANSION CHAMBER FOR PRESSURE CORE BARRELS BY AJ. Cmk

ATro-RNEY.

Patented June30, 1942 v ORE BABBELS Benjamin W. Sewell, Tulsa, Okla.,`assignor to Standard Oil Development Company -acor- Y poration ofDelaware Application February l0, 1940. Serial No. 318,266

(ci. ess-12) .claima The present invention relates to expansion membersfor pressure core barrels. It is an object of the present invention toprovide a pressure core'barrel with means for reducing the differentialpressure in the barrel when it is withdrawn to the surface of the earth.

It is a further object of the present invention to provide a pressurecore barrel with expansible means which will allow the pressure chamberto increase in volume as the core barrel is withdrawn to the surface ofthe earth and thereby reduce the pressure dlerential within the corebarrel.

Another object of the present invention is to provide a core barrel withmeans which will rev tain the fiuid'in the barrel and yet allow thepressure in the barrel to -be substantially reduced below the pressureof the formation from which the core is obtained.

Other objects and advantages of -the present I invention may be seenfrom reading the following description and by reference to theaccompanying drawings in which:

Fig. 1 is a cross sectional view of a portion of a. pressure core barrelshowing one modication of the present invention applied thereto;

Fig.2 is a cross sectional view of a portion of a core barrel similar tothat shown in Fig. 1 having yapplied thereto another modication of thepresent invention;

Fig. 3 is a cross sectional view of a portion of a core barrel showingapplied thereto another modicationofthe present invention, while Fig. 4shows the Asame portion of a core barrel illustrated in Fig. 3having-.applied thereto still another modification of the presentinvention.

to Flai, numeral 5 isa cylinder which 'forms a portion of a drill stem.Concentrlcally inside of cylinderv 5 is cylinder 35 whichis provided atits upper end with a cylindrical block 36 provided with a centralpassage 31. Central passage 31 is enlarged at its lower end to provideannular space 38. At the lower end of annular space 38 is downwardlyextending knife edge 53. A radial passage 39' connects space 38witlr'the exterior of the block. The block is also provided with alaterally offset longitudinal passage 40, controlled by a needle valve4l and", when open, making connection with a lateral passage l2 providedwith a plug d3 Afor the purpose hereinafter specified. Block 36`isprovided radially extending longitudinal fins ad which space it fromcylinder 5.

ceive a core. This core receivlngcylinder is connected to collar 5lwhich, in turn, is connected to the lower end of rod 25. y As may beseen in the drawings, rod extends upwardly through centrai passage 31and is connected at its upper end While the present invention maybeappliedf generally to pressure core barrels, it isv shown in the presentapplication as applied to the pressure core barrel described in myPatent 2,238,-

609 o i April 15, 1941 to facilitate the description thereof, parts aredesignated by the same numerals asare applied to like parts in theabovel mentioned copending application. The complete pressure corebarrel described in said patent has not been shown in the presentapplication because the means herein described are applicable topressure core barrels in general and are not dependent on the mechanismused in any particular core barrel. The operation of the presentinvention and its relationship to pressure core barrels will be clearlyunderstood from the folonvgvsing description of the accompanyingdrawaferrmg to die drawings and am 55.

with a coupling 2li which, in turn, is connected to a rod 20. Collar 5lis provided with a laterally extending upper face upon which is.arranged a strip of resilient material 52 of such dimensions as to formseat for the knife edge 53 for reasons ,which will be hereinafterexplained.

' Extending upwardly from block 36 is a sleeve de concentric with,vcoupling 2B, said sleeve normally having a .smaller inner diameter thanthe outside diameter of coupling 2l. but being reamed out to form asliding t for said coupling for a length defined by shoulders and 48,whereby said vcoupling is permitted limited longitudinal movement withinsaid sleeve' for the purpose hereinafter specified. p

At its upper end sleeve Il is provided with radially extendinglongitudinally arranged iins 41 which have inclined upper edges I8adapted to form ai' seat for the bevelled edge 49. of the inside edge othe lower end of a cylindrical section 1. Sectio 1 is also providedadjacent its lower end with a external shoulder 50. There is a linkagebetween ection -1 and the upper end of rod 20 which is not shown in thedrawings.

In this figure an expandable means is provided by a rubber sleeve Iliwhich embraces metal cylinder 35. Clamps |02 form a fluid-tight jointbetween-sleeve IUI and cylinder 3.5 at the endsexpandable a core in themanner conventional to the art and as the solid core enters the cylinder35 it displaces drilling fluid through passage Il. After a suitable corehas been cut, an upward pull is communicated from sleeve 1 through thelocking means, not shown, to rod 2l which. in turn.`

communicates the pull through collar 2l, rod 25 and collar I to theinner core barrel (not shown). This upward pull withdraws the inner corebarrel within cylinder 3l and allows a valve (not shown) at.the lowerend'of cylinder 35 to A continued pull draws collar 5| provided close.with seat 52 against knife edge 53 eilectivelyclosing the upper portionof cylinder 35. With Acylinder 35 sealed on'. at the upper and' lowerend the core barrel containing the core may Abe withdrawn to the surfaceof the earth.

` It will be appreciated that, when the core is obtained. it is sealedin a duid-tight manner under the pressure of the formation from which itis obtained and that ordinarily, as the core barrel is withdrawn to thesurface of the earth.

the -pressure differential becomes successively greater because thepressure on the exterior of the cylinder holding the core`becomes' lessand: less, while the pressure within it remains constant. However, inthe present'case cylinder 35 is provided with expansible sleeve lliwhich allows the gases within the pressure core barrel to expand. At theformation pressure the gases in the core occupy only a small part ol?`the total volume occupied by the core, so the volume required for gasexpansion in order to greatly reduce the pressure within the barrel neednot be large. It will be understood that the volume required. forexpansion may be several times larger than the volume required tocontain the core itself, but that this volume is not large compared withthe great pressure reduction obtained. For example. it is preferred tokeep the differential pressure within the core barrel at from fifty toone hundred pounds 'per square inch when the device is withdrawn to thesurface of the earth, and 'at times the formation pressure under whichthe core is sealed within the barrel may be as great as four thousandpounds per square inch. It will be understood that the drawing is notshown Ato scale and that communicates with the interior of the corebarrel in this figure the cylindrical head 36 is proarubber balloon.

the lower portion of arm 41 is of such dimensions as to provide room forthe expansible member |05. It will be understood that in withdrawing thedevice from' the bore hole shoulder 41 moves upwardly with respect'tothe upper face of block 35, seals the upper end of cylinder I5 and, inso doing, increases the space in which the Sylphon bellows l I5 mayexpand in order to reduce the pressure within cylinder 25.

Fig. 3 is a view of the portion oi' the core barrels illustrated in thepreceding fisuras provided with an expansible member |05 in the form o!This device is operated in the same general manneras the Sylphon bellowsshownin Fig. 2, the only dinerence being that a balloon is used as theexpansible member in stead of the Sylphon bellows.

In Fig. 4, aa modincation of the 4invention is shown in which theexpansion member is telescoping member |01. -The device shown in thisfigure operates in the same manner as that shown in Figs. 2 and 3.

While I have shown the modiiication o! the present invention as appliedto the core barrel described in my copending application Serial No.269.168, it will be apparent that these medidostions may be applied tothe pressure core barrels shown in copending Patents Nos. 2,213,595 ofSept. 13, 1940, and 2,216,962 of Oct. 8, 1940, and copending applicationNo. 310,284 filed Dec. 21, 1939. The modifications of the presentinvention may be applied not only to any of the above mentioned corebarrels, but also to other pressure core barrels to which an expansiblemember may be attached to allow the pressure within the. core barrel tobe reduced as the core barrel is withdrawn from the bore hole to thesurface.

of the earth.

Having fully described and illustrated the present invention, what Idesire to claimvis:

1. In a pressure core barrel provided with a pressure chamber adaptedtobe closed in a fluidtight manner, a duid-tight expansible member fluidlyconnected to the pressure chamber.

2. A pressure core barrel comprising .a cylin- 4. An apparatus inaccordance with claim 3 in which the expansible-member comprises arubber sleeve circumferentially embracing the cylindrical member andprovided with clamps firmly attaching its ends to said cylindricalmember.

5. An apparatus in accordance with claim 3 in which a .chamber havingexpansible walls-is attached to the upper end of the core barrel and bya passage through its upper end.

6. Anv apparatus in accordance with claim 3 in which the expansiblemember is a telescoping device arranged in the upper end of said corebarrel.

BENJAMIN W. SEWELL.

